Construction of the tunnel on the 92 road

Tunnelling
Nordfjordur, Iceland

The Norðfjarðargöng road tunnel is the longest Icelandic tunnel with a total mined length of over 7.5 km.

Basic information

Project Investor:

Vegagerdin Iceland

Project Designer:

Mannvit hf. Engineering Reyjkjavik

Project Duration:

09/2013 – 09/2017

Characteristics

The Norðfjarðargöng road tunnel is the longest Icelandic tunnel with a total mined length of over 7.5 km. The project included, in addition to tunnel mining, several partial building structures, such as new roads outside the tunnel, necessary insulation against penetrating water and freezing. When the mining was completed, the excavated tunnels were constructed at both portals, the technological rooms and their equipment, and the complete telematics of the tunnel. The tunnel is mined using the Drill & Blast method.

Project in numbers

  • 7908 m The total length of the tunnel
  • 566 m3 Mined part
  • 342 m The length of the excavated sections
  • 343 000 m3 The total cubature of mined parts
  • 54,7 m2 Tunnel profile (two road lanes)
  • 77,3 m2 Tunnel profile in safety bays (three road lanes)

Exceptionality of the structure

Tunneling conditions on Iceland are challenging. This is especially because mining often leads through rocks of very different qualities, so-called mixed face. Groundwater leaks and mining through fault-zones and basalt veins are also frequent.

The tunnel route runs through a mountain ridge with the highest mountain being Tvifjöll, at a height of more than 1,000 m above sea level. The work was carried out from both tunnel portals with a height above sea level of 25 or 60 m. From the western portal Eskifjörður, a total of 4,740 m of tunnel were excavated and a total of 2,826 m from the eastern portal Neskaupstaður. Excluding the last 400 meters of minings from the eastern portal, Mannvit hf. raised the tunnel with a pitch from 1.5 to 3%. The entire tunnel route leads in curves with different radii ranging from 700 m to 12,000 m. The maximum height of the cover was almost 900 m.